Fan system with variable air volume control

摘要

A centrifugal fan apparatus for installation in an air plenum adapted to provide pressurized air to a ventilating system includes a centrifugal fan rotor having front and rear sidewalls and a number of blades extending between these sidewalls. The platform has a horizontal base frame on which wheels are rotatably mounted. The front sidewall has a central opening for receiving air while the rear sidewall is attached to a rotatable drive shaft that extends rearwardly from the rotor. A motor is connected to the shaft in order to rotate it and the rotor. A linearly movable platform supports the rotor, shaft and motor and an actuator moves this platform forwardly or rearwardly in order to control the volume of air flowing out of the rotor. An air inlet member is mounted rigidly at the central opening and has a generally cylindrical section that can extend into the rotor when the rotor is moved to a forward position.